Wafer polishing apparatus and polishing method

Abstract

A wafer polishing apparatus has a rotary polishing bed, an abrasive cloth provided on the polishing bed, an abrasive supply supplying abrasives to a surface of the abrasive cloth, a wafer depressor depressing the wafer onto the abrasive cloth at a predetermined pressure, a ring shaped retainer arranged surrounding the wafer and provided with a plurality of grooves extending between an inner peripheral edge and an outer peripheral edge on a surface contacting with the abrasive cloth, a rotary driver driving the wafer and the retainer on the abrasive cloth, and a rotation speed difference generator providing a difference of rotation speeds between the wafer and the retainer.

What is claimed is:  
     
       1. A wafer polishing apparatus comprising: 
       a rotary polishing bed;  
       an abrasive cloth provided on said polishing bed;  
       abrasives supplying means for supplying abrasives to a surface of said abrasive cloth;  
       wafer depressing means for depressing said wafer onto said abrasive cloth at a first pressure;  
       a ring shaped retainer arranged surrounding said wafer and provided with a plurality of grooves extending between an inner peripheral edge and an outer peripheral edge on a surface contacting with said abrasive cloth;  
       rotary driving means for driving said wafer and said retainer on said abrasive cloth; and  
       rotation speed difference generating means for providing a difference of rotation speeds between said wafer and said retainer.  
     
     
       2. A wafer polishing apparatus as set forth in claim  1 , wherein said plurality of grooves provided in said retainer extend along a plurality of straight lines extending through a center point of said wafer and are linear shaped configuration. 
     
     
       3. A wafer polishing apparatus as set forth in claim  1 , wherein said plurality of grooves provided in said retainer extend along predetermined streamlines of said abrasives determined by a rotation speed of said polishing bed and the rotation speed of said retainer. 
     
     
       4. A wafer polishing apparatus as set forth in claim  1 , wherein said plurality of grooves provided in said retainer extend oblique with respect to a plurality of straight lines extending through the center points of said wafer at a predetermined angle and are linear shaped configuration. 
     
     
       5. A wafer polishing apparatus as set forth in claim  1 , wherein said plurality of grooves provided in said retainer extend oblique with respect to a plurality of straight lines extending through the center points of said wafer at a predetermined angle and are curved shaped configuration. 
     
     
       6. A wafer polishing apparatus as set forth in claim  1 , wherein rotation speed difference generating means comprises a bearing disposed between said rotary driving means for driving to rotate said wafer and said retainer, and said retainer, and rotation preventing means for preventing rotation of said retainer. 
     
     
       7. A wafer polishing apparatus as set forth in claim  1 , wherein said rotary driving means is provided for each of said wafer and said retainer independently of the other, and said rotation speed difference generating means includes two rotation control means respectively controlling rotating direction and rotation speed of respective rotary driving means independently of the other. 
     
     
       8. A wafer polishing method comprising the steps of: 
       supplying an abrasive to a surface of an abrasive cloth provided on a rotary polishing bed;  
       driving a wafer as an object for polishing and a retainer arranged surrounding said wafer for rotation with depressing said wafer onto said abrasive cloth at a first pressure by said retainer; and  
       causing a difference of rotation speeds of said wafer and said retainer.  
     
     
       9. A wafer polishing method comprising the steps of: 
       supplying an abrasive to a surface of an abrasive cloth provided on a rotary polishing bed;  
       driving a wafer as an object for polishing and a retainer arranged surrounding said wafer for rotation with depressing said wafer onto said abrasive cloth at a first pressure by said retainer, in which said abrasive is supplied to a surface of said wafer to be polished in one rotating direction of said wafer and said retainer, and said abrasive is discharged from said surface of said wafer to be polished in the other rotating direction; and  
       switching rotating direction between said one direction to the other direction.  
     
     
       10. A wafer polishing method as set forth in claim  9 , wherein a plurality of grooves extending oblique relative to straight lines extending through a center point of said wafer with a predetermined angle, are provided on a surface of said retainer contacting with said abrasive cloth, in such a manner that said abrasive is supplied to a surface of said wafer to be polished in one rotating direction of said wafer and said retainer, and said abrasive is discharged from said surface of said wafer to be polished in the other rotating direction. 
     
     
       11. A wafer polishing method as set forth in claim  9 , wherein switching of rotating direction of rotation of said retainer on said abrasive cloth is repeated according to a fixed sequence.